Dry cell



Dec. 1,1925- 1,563,628

W. F. HENDRY DRY CELL Filed I3? 26, 192 3 INVENTOR ATTORNE Y Patented Dec. 1, 1925.

UNITED STATES 1,563,628 PATENT OFFICE.

WILLIAM F. ILENDRY, 0F OSSINING, NEW YORK, ASSIGNOR TO THE MANHATTAN ELECTRICAL SUPPLY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MASSA- GHUSETTS.

DRY CELL.

Application filed May 28, 1923. Serial No. 641,696.

To all whom it may concern:

Be it known that I, W ILLIAM F. Hnnnnr, residing at Ossinin New York, in the county of Vi estchest-er and State of New York, United States of America, having invented certain new and useful Improvements in Dry Cells, do hereby declare thatthe following is a full, clear, and exact description of the same.

This invention relates to dry cells, and more particularly to improvements in the construction of metallic electrodes such as cylindrical zinc electrodes used in dry cells.

As well-known, the metallic e. g. zinc electrodes are usually constructed in the form of a cylinder surrounding a centrally located electrode, e. g. of carbon, a suitable depolarizer and the paste holding the electrolyte. The zinc cylinder or can is formed by rolling up a sheet of zinc of suitable size and then soldering the two overlapping edges of the sheet.

The handling of the zinc sheet during the soldering operation is rather difficult, because it is necessary to hold zinc in the rolled up condition while the solder is applied and until it cools off. This, of course, slows down and complicates the operation of automatic machinery that is employed in making such zinc cans.

In order to obviate this difliculty and to speed up the process, attempts have been made to draw the zinc cans, or mechanically to connect, e. g. by means of lugs, lock-seams, or the like the overlapping edges of the zinc sheet. lHowever, zinc and other metal cans made in that manner were not satisfactory. Dry cells made of such zinc cans were short lived because the metal corroded or ate away quickly at points that were placed under strain during the mannfacturing or assembling process. The reason for this resides probably in that strained points on the zinc become positive whereby local currents will be set up between adjacent points of the electrode. Whatever the reasons may be therefor, it has been found that the zinc will be consumed more quickly at points that were placed under strain than at other points. For this reason, notwithstanding the above mentioned advantages, the soldering of zinc cans continued in the first mentioned manner.

In accordance with the present invention,

the cost of making zinc cans or the like for dry vcells is materially reduced by holding together adjacent edges of the zinc sheet by a lock sea-m, by crimping or any other suit able folding, interlocking or holding means, and applying an insulating coating to those points of the metal which were placed under strain. The seams may then be easily soldered 1n the manner well-known in can making.

Preferably. the zinc can or the like is assembled by first applying the insulating coating to one edge of the sheet of zinc, then clamping or otherwise locking together two edges of the sheet in a manner that the protected edge will be inside, and will therefore be the one which comes into contact with the electrolyte. The application of a coating of paint after the forming of the seam would render the operation too expensive.

In accordance with the present invention, an acid proof insulating paint made of asphaltum, bakelite or the like is used for coating the metallic electrode, and the paint is applied only to the points which are placed under strain. If, for instance, the wellknown lock-seam is used then only a narrow edge of the sheet need be coated. Obviously, any suitable paint or coating may be used for this purpose, and the application of such coating will vary depending on the method or means used in holding together the two edges of the zinc. If necessary, both edges of the sheet of zinc may be coated.

For the purpose of more clearly illustrating one embodiment of the invention, in the enclosed drawing Fig. 1 shows a sheet of zinc l lying fiat and one edge thereof covered with a suitable insulating paint at 2. Fig. 2 is a top view of the zinc sheet 1 rolled into a cylinder, with the opposing ends held together by means of a lock-seam, the painted strip 2 being exposed to the electrolyte in the cell. In forming the lock-seam only (he interlocking edges will be subjected to strain, and of these only the one on the inside will come into contact with the electrolyte. The insulation 2 protects the strained portions of the zinc can against the chemical action that takes place in dry cells. The chemical action on the other parts of the zinc will occur .in the usual manner.

VVhat- I claim is:

1. In a dry cell, a cylindrical casing of zinc held together by one edge being folded over the opposite edge of a sheet of zinc, and an insulating coating covering the inside edge of the zinc throughout its length.

2. In a dry cell, a cylindrical casing of zinc held together by means of a lock seam joint, and an acid proot' insulating paint entirely covering that portion of the inside of said casing which was placed under strain by said lock-seam.

3. The process of making zinc cans for dry cells which consists in first applying a coating of insulation to one edge of a sheet of zinc, and then permanently connecting 15 said one edge to the opposite edge with the insulation on the inside of the can.

4. The process of making Zinc cans for dry cells which consists in first applying a coating of insulating paint to one edge of a sheet of zinc, then rolling the sheet and folding said one edge and the opposite edge to form a lock-seam with the paint on the inside of the can and finally in soldering the seam on the outside of the can.

In witness whereof, I hereunto suloscrihe my name this23rd day of May, 1923.

WILLIAM F. HENDRY. 

